1. Field of the Invention
This invention is directed toward expression vectors which permit expression of heterologous genes in mammalian tissue, including humans. In particular, this invention provides a DNA sequence which promotes gene expression preferentially in hippocampal tissue.
2. Related Art
A dramatic example of cell specific gene expression is illustrated by the .gamma.-aminobutyric acid type A (GABA.sub.A) receptor gene family in the nervous system. A number of the GABA.sub.A receptor genes display preferential expression in only one region of the brain, while expression in other brain regions is barely detectable. In particular, .beta.1 subunit gene expression is highest in the pyramidal neurons of the hippocampus, making it a prime candidate for the study of cell-specific regulation.
Small molecules such as acetylcholine, glutamate, .gamma.-aminobutyric acid (GABA), and glycine serve as the major neurotransmitter that carry signals from the presynaptic nerve terminal to the postsynaptic membrane. Inhibitory neural transmission is a central component of information processing for both vertebrates and invertebrates, and GABA is the major transmitter at inhibitory chemical synapses. Virtually all neurons in the vertebrate nervous system are sensitive to GABA with inhibitory synaptic activity being mediated through the GABA.sub.A receptor.